/*
    FreeRTOS V6.0.4 - Copyright (C) 2010 Real Time Engineers Ltd.

    ***************************************************************************
    *                                                                         *
    * If you are:                                                             *
    *                                                                         *
    *    + New to FreeRTOS,                                                   *
    *    + Wanting to learn FreeRTOS or multitasking in general quickly       *
    *    + Looking for basic training,                                        *
    *    + Wanting to improve your FreeRTOS skills and productivity           *
    *                                                                         *
    * then take a look at the FreeRTOS eBook                                  *
    *                                                                         *
    *        "Using the FreeRTOS Real Time Kernel - a Practical Guide"        *
    *                  http://www.FreeRTOS.org/Documentation                  *
    *                                                                         *
    * A pdf reference manual is also available.  Both are usually delivered   *
    * to your inbox within 20 minutes to two hours when purchased between 8am *
    * and 8pm GMT (although please allow up to 24 hours in case of            *
    * exceptional circumstances).  Thank you for your support!                *
    *                                                                         *
    ***************************************************************************

    This file is part of the FreeRTOS distribution.

    FreeRTOS is free software; you can redistribute it and/or modify it under
    the terms of the GNU General Public License (version 2) as published by the
    Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
    ***NOTE*** The exception to the GPL is included to allow you to distribute
    a combined work that includes FreeRTOS without being obliged to provide the
    source code for proprietary components outside of the FreeRTOS kernel.
    FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
    more details. You should have received a copy of the GNU General Public 
    License and the FreeRTOS license exception along with FreeRTOS; if not it 
    can be viewed here: http://www.freertos.org/a00114.html and also obtained 
    by writing to Richard Barry, contact details for whom are available on the
    FreeRTOS WEB site.

    1 tab == 4 spaces!

    http://www.FreeRTOS.org - Documentation, latest information, license and
    contact details.

    http://www.SafeRTOS.com - A version that is certified for use in safety
    critical systems.

    http://www.OpenRTOS.com - Commercial support, development, porting,
    licensing and training services.
*/


#include <stdlib.h>
#include "FreeRTOS.h"
#include "list.h"

/*-----------------------------------------------------------
 * PUBLIC LIST API documented in list.h
 *----------------------------------------------------------*/

void
vListInitialise (xList * pxList)
{
  /* The list structure contains a list item which is used to mark the
     end of the list.  To initialise the list the list end is inserted
     as the only list entry. */
  pxList->pxIndex = (xListItem *) & (pxList->xListEnd);

  /* The list end value is the highest possible value in the list to
     ensure it remains at the end of the list. */
  pxList->xListEnd.xItemValue = portMAX_DELAY;

  /* The list end next and previous pointers point to itself so we know
     when the list is empty. */
  pxList->xListEnd.pxNext = (xListItem *) & (pxList->xListEnd);
  pxList->xListEnd.pxPrevious = (xListItem *) & (pxList->xListEnd);

  pxList->uxNumberOfItems = 0;
}

/*-----------------------------------------------------------*/

void
vListInitialiseItem (xListItem * pxItem)
{
  /* Make sure the list item is not recorded as being on a list. */
  pxItem->pvContainer = NULL;
}

/*-----------------------------------------------------------*/

void
vListInsertEnd (xList * pxList, xListItem * pxNewListItem)
{
  volatile xListItem *pxIndex;

  /* Insert a new list item into pxList, but rather than sort the list,
     makes the new list item the last item to be removed by a call to
     pvListGetOwnerOfNextEntry.  This means it has to be the item pointed to by
     the pxIndex member. */
  pxIndex = pxList->pxIndex;

  pxNewListItem->pxNext = pxIndex->pxNext;
  pxNewListItem->pxPrevious = pxList->pxIndex;
  pxIndex->pxNext->pxPrevious = (volatile xListItem *) pxNewListItem;
  pxIndex->pxNext = (volatile xListItem *) pxNewListItem;
  pxList->pxIndex = (volatile xListItem *) pxNewListItem;

  /* Remember which list the item is in. */
  pxNewListItem->pvContainer = (void *) pxList;

  (pxList->uxNumberOfItems)++;
}

/*-----------------------------------------------------------*/

void
vListInsert (xList * pxList, xListItem * pxNewListItem)
{
  volatile xListItem *pxIterator;
  portTickType xValueOfInsertion;

  /* Insert the new list item into the list, sorted in ulListItem order. */
  xValueOfInsertion = pxNewListItem->xItemValue;

  /* If the list already contains a list item with the same item value then
     the new list item should be placed after it.  This ensures that TCB's which
     are stored in ready lists (all of which have the same ulListItem value)
     get an equal share of the CPU.  However, if the xItemValue is the same as 
     the back marker the iteration loop below will not end.  This means we need
     to guard against this by checking the value first and modifying the 
     algorithm slightly if necessary. */
  if (xValueOfInsertion == portMAX_DELAY)
    {
      pxIterator = pxList->xListEnd.pxPrevious;
    }
  else
    {
      /* *** NOTE ***********************************************************
         If you find your application is crashing here then likely causes are:
         1) Stack overflow - 
         see http://www.freertos.org/Stacks-and-stack-overflow-checking.html
         2) Incorrect interrupt priority assignment, especially on Cortex M3 
         parts where numerically high priority values denote low actual 
         interrupt priories, which can seem counter intuitive.  See 
         configMAX_SYSCALL_INTERRUPT_PRIORITY on http://www.freertos.org/a00110.html
         3) Calling an API function from within a critical section or when
         the scheduler is suspended.
         4) Using a queue or semaphore before it has been initialised or
         before the scheduler has been started (are interrupts firing
         before vTaskStartScheduler() has been called?).
         See http://www.freertos.org/FAQHelp.html for more tips. 
         ********************************************************************* */

      for (pxIterator = (xListItem *) & (pxList->xListEnd);
	   pxIterator->pxNext->xItemValue <= xValueOfInsertion;
	   pxIterator = pxIterator->pxNext)
	{
	  /* There is nothing to do here, we are just iterating to the
	     wanted insertion position. */
	}
    }

  pxNewListItem->pxNext = pxIterator->pxNext;
  pxNewListItem->pxNext->pxPrevious = (volatile xListItem *) pxNewListItem;
  pxNewListItem->pxPrevious = pxIterator;
  pxIterator->pxNext = (volatile xListItem *) pxNewListItem;

  /* Remember which list the item is in.  This allows fast removal of the
     item later. */
  pxNewListItem->pvContainer = (void *) pxList;

  (pxList->uxNumberOfItems)++;
}

/*-----------------------------------------------------------*/

void
vListRemove (xListItem * pxItemToRemove)
{
  xList *pxList;

  pxItemToRemove->pxNext->pxPrevious = pxItemToRemove->pxPrevious;
  pxItemToRemove->pxPrevious->pxNext = pxItemToRemove->pxNext;

  /* The list item knows which list it is in.  Obtain the list from the list
     item. */
  pxList = (xList *) pxItemToRemove->pvContainer;

  /* Make sure the index is left pointing to a valid item. */
  if (pxList->pxIndex == pxItemToRemove)
    {
      pxList->pxIndex = pxItemToRemove->pxPrevious;
    }

  pxItemToRemove->pvContainer = NULL;
  (pxList->uxNumberOfItems)--;
}

/*-----------------------------------------------------------*/
